Spatio-temporal characterization of intertidal macrofauna at prainha beach (Rio de Janeiro State)
Keywords:macrofauna, sandy beaches, intertidal region, zonation
Variations in the density, richness and distribution ofthe intertidal macro fauna species were studied on a sandy beach along time. Monthly samples were taken from June 1993 through May 1995 at Prainha beach, State of Rio de Janeiro. Three transects were established, each with five strata parallel to the waterline. Strata were located between above drift line zone and the upper of the sublittoral area. From each stratum four replicates were randomly taken with a 0.04 mÂ² sampler. This beach is constituted by medium sands (0.40 to 0.49 mm). The slope varied from 1/5.26 to 1/12.99 and the width of the beach varied from 46.7 to 63.2m. Prainha was classified as a reflective beach (Dean's ? = 1.13). Monthly richness varied from 4 to 7 species. Emerita brasiliensis (Decapoda), Excirolana braziliensis (Isopoda) and Pseudorchestoidea brasiliensis (Amphipoda) were the main species accounting for 95 % of the community. The abundance of these three species varied continuously along the sampling period. Emerita brasiliensis was more abundant in summer and spring; followed by P. brasiliensis in autumn. E. braziliensis was more abundant in winter. Seasonal variation in the density of the macrofauna was connected with recruitment and reproduction activities. The supralittoral zone was characterized by holes of the ghost crab Ocypode quadrata and Phalería testacea. E. braziliensis and P. brasiliensis showed continuous migration in the midlittoral zone, occupying the same stratum in most of the months. Emerita brasiliensis characterized the upper sublittoral area.